Comparison of pain detection thresholds in patients with migraine, tension type headache and asymptomatic controls: generalized or peripheral pain sensitization?

Background Sensitization is a key phenomenon in headache pathophysiology.
To determine the presence of sensitization, pain detection
thresholds (thermal and pressure stimuli) of patients with migraine
(n = 39) and tension type headache (TTH, n = 21) were compared
with those of asymptomatic controls (n = 50 for pressure stimuli,
n = 30 for thermal stimuli). All patients were diagnosed by an
experienced neurologist according to the 2004 criteria of the International
Headache Society. Patients mean age and Headache Impact
Test score (HIT-6) were 33.9 y. ± 11.7 years and 66.4 ± 5.6 points,
respectively.
Pain detection thresholds were assessed by means of the 'method of
limits'. All measurements were performed bilaterally, both on
cephalic and extracephalic sites. Cephalic sites were the temple and
mastoid process, extracephalic sites were the index and anterior tibial
muscle (pressure stimuli) or thenar (thermal stimuli).
Results In comparison with asymptomatic controls, both migraine
and TTH patients showed lower pain detection thresholds (both for
pressure as well as for thermal stimuli) on cephalic sites but not on
extra-cephalic sites.
No significant differences in pain detection thresholds were found
between patients with migraine and TTH.
Patients with more than 15 headache days per month showed no
statistically significant additional lowered pain detection thresholds,
although a trend could be observed for migraine patients only.
Conclusions Reduced pain detection threshold on cephalic sites was
found in patients with migraine and TTH. This indicates sensitization
of polymodal receptors which, from this study, appears to be
peripheral rather than central. The trend for an additional lowered
pain detection threshold in chronic migraine patients needs clarification
in larger patients samples.